I might recommend you start Qi-Gong, or some authentic energy manipulation art. After 20 years of practicing or so (If one has a good teacher/school), things can get pretty interesting internally. This type of hobby is a prerequisite for shaolin monks who want to go further into the depths of zen meditation. (which would be quite dangerous at advanced levels without qi-gong allowing them to control their internal organizational cell energy (or Qi/Prana in Asian terms))